Pneumatic tool



AJun@ 8,1926. 1,587,611

' y W. A. SMITH PNEUMATIC TOOL f Filed Sept. 5. 1922 2 Sheets-Sheet 1 "F1a-l.

111.11mA R .Smm-

June 8 1926. 1,587,611

w. A. SMITH -PNEUMATIC Tool.

Filed sept. 5, 1922 2 sheetsfsheet '2 CTI Patented June 8, 1926.v

UNITED'STATES PATENT OFFICE.

WILLIAM A. SMITH, OIE DETROIT, MICHIGAN ASSIGNOR TO CHICAGO PNEUMATIC TOOL COMPANY, 0F NEW YORK, N. Y., A CORPORATION 0F NEW JERSEY.

PNEUMATIC Toor..

Application med september 5, 1932. 'serialieo. 586,290. i

valve in a retracted position in order thatk Aair may be admitted from the cylinder to the hollow drilling tool for the purpose of blowing out the cuttings from deep drill holes during the drilling operation.

ln the drawings Figure 1 is a longitudinal section through the tool showing the normal operation of the drill;

Figure 2 is a longitudinal section showing the spool valve manually held in retracted position;

Figure 3 is a fragmentary section on the line 3--3 of Figure 2.

1 is a cylinder containing a piston 2having a shank portion 3 engaging the piston guide 4 and impinging against the end of the tool 5 therein. ln the construction shown the tool 5 is arock drill and is provided with a longitudinal bore 6 for, admitting air to the end of the tool to blow out the cuttings from the drill holes. The iston shank 3 has a passageway-7 exten ing longitudinally thereof so that in the retracted position of said piston air is admitted from the cylinder to the chamber 8 in the piston guide 4.

rllhe spool valve 9 is reciprocable within a valve cylinder 10 at one side of the main cylinder and comprises essentially .the head portions 11 and 12. a central head or disk 13, preferably ot greater diameter than the head portions and intermediate grooves or annular chambers V14 and 15 forming the main air feeding passages. ln order that the spool valve may be assembled within the valve cylinder there is provlded the bushing 16 forming the rear head of the valve cylinder. The bushing is inserted 1n the rear end of the valve cylinder casing and contains the internal bore 17 in which the valve head 12 is slidable. Centrally of the valve cylinder is an annular port 18 controlled by the disk 13'to be placed alternately in communication with the grooves 14 and 15.

The head portions of the spool valve are hollow having the openings 19 and 20 in the respective end faces and the valve is provided with a longitudinal bore 21 which communicates with the openin 19 but is separated from the opening 20 y a partition 22. The portion of the valve cylinder casmg forming the forward head of the valve cylinder contains a bore 23 in axial align` ment with the valve cylinder 10 in which is slidably mounted a valve stem 24 having one end projecting beyond the casing and the other end extending within the bore 21 of the valve. rlhe valve stem is manually operable so that by pressing the projecting end the inner end engages the partition 22 and holds the valve in its rear position. lVhen the valve stem is not manually pressed a collar 25 engages with the forward end of the valve cylinder. In this latter position a vent port 26 is open to the atmosphere and communicates through a longitudinal bore s 27 in the valve stem with the interior of the lspool valve.

However, the ventport 26 is sealed within the bore 23 when the valve stem is manually depressed.

Live air is admitted through the inlet 28 communicating directly with the annular port 18. Pressure is communicated to the main cylinder through the passageways 29 and 30, the former leading from the annular chamber 14 to the forward end of the cylinder and the latter corresponding from the annular chamber 15 to the rear end of the cylinder'. rll`he exhaust passages 31 and 32 are alternatelyy connected by the shifting ofk the spool valve to the annular chambers 14: and 15 so that one chamber is connected to the inlet and the other'to the exhaust in each position of the valve. Between the midpoint of the main cylinder and its rear end is a port 33 overrun by the piston 2 and conimunicating with the forward end of the valve cylinder through a passageway 34. From the rear end ot the valve cylinder thereis a passageway 35 which leads to a port 36 in the main cylinder between the mid-point and its forward end. This port is formed with an elongated extension 3T from which a vent port 38 leads to the atmosphere. rllhus when the piston is in a position to seal the vent port 36 pressure upon the valve head 12 may be exhausted to the atmosphere through port 38 but when the piston is at the rear endet its stroke the port 38 will communicate with the main cylinder but not directly with the valve cylinder. 39 is a leak passage between the passageways 29 and 34: which is so restricted lll() lili that when the valve 24 is in its normal or extended position as in F ig. 1 any fluid passing through the leak passage will be eX- hausted to the atmosphere through the bore 2l of the valve, bore 27 of the valve stem and vent port 26 without appreciable increase in pressure upon the valve head 1i.

ln the normal operation of the tool air enters through theinlet 28 and With'the valve in the position shown in Figure 1-the air passes through the annular chambers 18 and 14- and the passageway 29 to the forward end ot' the main cylinder where it drives the piston 2 rearwardly in the direction oit the arrow. The exhaust from the rear end oi the cylinder 21 passes out through the passageway 30, annular chamber and exhaust passage 82. The valve 9 is held in its rear position by reason of the larger effective area of the central disk 13. llfhen the piston has uncovered the port 36 and covered the porty 33 pressure is built up against the rear head 12 of the valve through the passageway 35 while pressure on the opposite valve head 11 is exhausted to the atmosphere through the bore 2l of 'the valve, the bore 270i the stem and vent port 26. The valve is thus thrown to its forward position reversing the inlet and exhaust connections.

Air now enters the rear end of the cylinder through inlet 28 and annular chambers 18 and 15 and passageway 3() and causes the piston to travel forward. The exhaust now takes place through passageway 29, annular chamber le and exhaust passage 31. As soon as the piston has covered the port 36 and uncovered the port 33 pressure on 'the valve head 12 is exhausted to the atmosphere through the vent port 38 while pressure is built up against the valve head 11 through the pasageway Se. ln this way the valve is caused to shift to its rear position again and this cycle continues during the normal operation of the tool.

When it is desired to blow the cuttings from the drill hole the valve stem 24: is manually operated forcing the valve in the position shown in Figure 2. llt will be noted that in this position the vent port 26 is sealed within the casing thereby preventing the escape of the air entering the valve cylinder through theleak passage 39. A pressure is, therefore, built up against the valve head 11 which counteracts the opposing pressure on the valve head 12. This together with the pressure exerted on the central disk 13 causes the valve to be held pneumatically in its rear positiom It is necessar however, to manually hold the' valve stem 24 against the pressure within the valve cylinder and as soon as the manual pressure is released the valve stem will resume its normal position and the tool will again function in its normal manner.

lWhen the valve is held in its retracted posi- Loenen tion by the depression of the valve stem the piston is also held in retracted position by the air entering the cylinder through the passage 29. The passage-way 7 then communicates between the main cylinder and the chamber 8 allowing live air to pass therethrough and enter the hollow drill 5. rlFhus by my improved conmruction it is possible to stop the normal `operation of the spool valve and to admit live air to the operating tool by manually operatingan auxiliary valve requiring 'only a very slight pressure.

W'hile l have shown a construction in which the spool valve may be held retracted `loathe purpose of admitting air to the cutting tool it isobvious that my invention is not limited to such a structure but that it might be applied for other purposes wherein it is desired to interfere with the automatic control of the spool valve without relieving the presure from the line.

llfhat l claim as my invention is 1. ln a percussive tool, the combination with a cylinder, a reciprocating piston therein and a reciprocatory valve pneumatically actuated and automatically controlled by the reciprocation of said piston, and means normally venting one side of the valve to atmosphere and operable to interfere pneumatically with the automatic actuation ot said valve to arrest movement thereof while still subjected to pneumatic pressure.

In a percussive tool, the combination with a cylinder, a reciprocatory piston therein and a reciprocatory valve pneumz'iticall)Y actuated and automatically controlled by the reciprocation of said piston, and means providing a normally open leak passage from one end ofthe valve to atmosphere and operable to close said leak passage thereby to interfere with the automatic reversal of pressure on said valve for arrestingmovement thereof while still subjected to pneumatic pressure.

3. In a percussive tool, the (,roinbinaton with a cylinder, a reciprocatory piston thorein and a pneuniatically actuated reciprocatory valve automatically controlled by said piston, of an auxiliary valve normally providing leakage of pressure from one end of said valve to atmosphere and operable to stop said leakage thereby to interfere with said automatic control to hold said valve in tired position.

ln a percussive tool, the combination with a cylinder, a piston operating therein, a hollow drill driven by said piston` and means for admitting fluid to said drill when said piston is in a retracted position, oi a spool valve controlling the reciprocation of said piston, and a manually operable valve normally permitting leakage of air Il-rom one end of said spool valve and o erable to stop said leakage and retain said lll) spool valve in a` position to retract said piston.

5. In a percussive tool, the combination with a cylinder, a piston operating therein, a hollow drill driven by said piston, and means for admitting fluid to said drill when said piston .is at the limit of its rearward movement, of a valve controlling the reciprocation of said piston, manually operable means directly engaging said valve for holding the latter-in a position to retract said iston, and means for pneumatically counteralancing the pressure tending to throw said valve.

6. In -a percussive tool, the combination with a cylinder, a piston operating therein, a hollow drill driven by said piston, and means for admitting fluid to said drill when said piston is in retracted position, of a hollow spool valve controlling the reciprocation of said piston, a passageway placing one end of said valve normally in communication with atmosphere and-a valve stem slidable within said valve and manuall operable to close said passageway whereby said valve is held in a position to retract said piston. I

7. Ina percussive tool, the combination with a cylinder, a piston operating therein, a hollow drill driven yby said piston, and means for admitting fluid to said drill when said piston is in aretracted position, of a hollow spool valve controlling the reciprocation of said piston, and a valve stem slidable within said spool valve having a leak passageway therein normally open to the atmosphere, said valve stem being manuallyV operable to hold said valve in a position to retract said piston.

8. In a percussive tool, the combination with a cylinder, a piston operating therein,

a hollow drill driven by said piston, and

means for admitting fluid to said drill when said piston is in a retracted position, of a hollow spool valve controlling the reciprocation of said piston, a yvalve stem slidable within said spoollvalve having a leak passage therein normally open to atmosphere, and a valve casing surrounding said valve and having a passageway for admitting fluid pressure to the valve, said pressure being normally relieved through said leak passage, said valve stein being manually operable to close said leak passage whereby the fluid pressure admitted by the passageway in the valve casing builds up to hold said valve in a position to retract said piston.

9. In a percussive tool, the combination of a valve cylinder, a spool valve reciprocable therein, means for alternately supplying fluid pressure to the opposite ends of said valve, a valve stem slidable within said valve and manually operable to hold the same in one position of adjustment, a restrictedinlet for introducing fluid ypressure into said cylinder to assist in holding said valve in said position, and a leak passage-normally exhausting said pressure, said passage being closed upon manual operation of said valve stem. j v

10. In a percussive tool, the combination of a valve cylinder, a spool valve reciprocable therein, means for alternately supplying fluid pressure ,to the opposite ends of said valve, a valve stem slidable within said valve and manually operable to hold the same in one position of adjustment, a rev stricted inlet for introducing fluid pressure to said cylinder to assist in holding said valve in said position, and a leak passage in said valve stern normally communicating with the atmosphere, said passage being closed upon manual operation of said valve stem.

ll. In a percussive tool, the combination of a valve cylinder, a spool valve reciprocable therein, means for alternately supplying fluid pressure 'to the opposite ends of said valve, a restricted inlet for introducing additional fluid pressure to one end of said valve, a leak passage normally exhausting the fluid pressure supplied by said inlet, and manually operable means for holding said valve in one position of adjustment and for simultaneously closing said leak passage.

12. In a percussive tool, the combination of a valve cylinder, a spool valve reciprocable therein, means for alternately supplying fluid pressure to the opposite ends of said valve, a restricted inlet for introducing additional fluid pressure tofone end of said valve, and a valve stem slidable within said valve having a leak passage therein normally exhausting the fluid pressure supplied by said inlet, said valve stein being manually operable to hold said valve in one position of adjustment and to simultaneously close said leak passage.

13. In a percussive tool, the combination with a cylinder, a piston operating therein` and a hollow drill driven by said piston, of a valve controlling the reciproeaton of said piston, a valve casing forming a cylinder for said valve, said casing being provided with 1 a hollow shank portion, and a valve stem slidable in said portion having a port normally open to the atmosphere, said valve stem being manually operable to hold said valve in retracted position, thereby sealing said port within said valve casing. v i

In testimony whereof I affix my signature.

. WILLIAM A. SMITH. 

